1. Technical Field
The invention relates to an insulation material based on polyvinyl chloride for use as a sheathing for long materials, where additives for flame retardation have been added to the base material, as well as stabilizers and processing aids.
2. Description of the Related Art
In the sense of the invention "long" materials could be electrical and optical cables or wires as well as wire conduits. In this case electrical installation wires and so-called plenum cables, which are installed in buildings to supply power to the most diverse users and for transmitting information, are of particular interest. Polyvinyl chloride (PVC) is the insulation material used in most of these wires. Although it has good electrical properties, PVC however has the disadvantage that in case of fire the halogen contained therein is liberated as a hydrogen compound. The PVC decomposes when heavy smoke production takes place. PVC therefore does not fulfill today's requirements for a material that can be used for wires installed in buildings, unless suitable additives are added. In case of fire such insulation material should not release toxic gases and should especially not give off any disabling smoke.
To avoid these disadvantages, filler materials that are able to form acids are added to the insulation material disclosed in GB 1 260 533. The filler materials are for example small particle thermostable metals such as alkaline earth metals. Specially mentioned are magnesium carbonate and calcium carbonate for example. The use of such an insulation material can avoid most of the toxic gas liberation in case of a fire. However the insulation material is able to burn and the development of smoke can therefore not be avoided.